Search

Thymol (TMO) was loaded into chitosan nanoparticles (CSNPs) to inhibit chestnuts decay during storage. Three chestnut treatments were evaluated, including the CK (uncoated control), CSNPs (coated with chitosan nanoparticles), and TMO-CSNPs (coated with thymol-loaded chitosan nanoparticles). Quality assessments of chestnuts were conducted periodically for up to 180 days, which included starch content, amylase activity, water content, respiration rate, weight loss rate, microbiological indicators, decay rate, and quality evaluation. Results indicated that TMO-CSNPs had significantly less nutrient loss in soluble sugar (10.61%) and starch content (27.72%) compared with CK, which was attributed to low metabolic activities as evident in low amylase activity and respiration rate. Moreover, TMO-CSNPs significantly inhibited the growth of mold and yeast (4.17 log CFU g -1 on day 180) and kept the lowest decay rate (5.33%). This study demonstrates the potential of food nanomaterial as an alternative strategy to promote food security and supply chain resilience., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Preservatives in processed meat raise significant concerns associated with bowel cancer and diabetes, and implicate various public health issues. This introduces the need for safer preservatives to uphold public health standards. However, developing safer alternatives to these preservatives poses a significant challenge to food industry. A potential solution to this issue is the use of loaded nanoparticles as preservative agents. This study investigated antimicrobial and antioxidant effects of sorbic acid-loaded chitosan/tripolyphosphate nanoparticles (SAN) in Chinese Sausage. SAN were prepared through ionic gelation, followed by natural air-drying for 20 days. After preparation, the antimicrobial and antioxidant activities of various treatment groups were analyzed intermittently during storage at room temperature. SAN-treated samples had significantly lower levels of surviving bacteria, molds, and yeasts than the blank control (p < 0.05) over the entire 72 days of storage. Additionally the SAN-treated samples also had lower levels of surviving bacteria than the chitosan/tripolyphosphate samples after 31-56 days of storage (p < 0.05). The thiobarbituric acid value and pH of the SAN-treated samples were also significantly lower than the blank control (p < 0.05). These results indicated that SAN could be a good intervention strategy to retard lipid oxidation and inhibit microbial growth in Chinese Sausage., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Chitosan (CS) nanoparticles coated with zein has been newly demonstrated as a promising encapsulation and delivery system for hydrophilic nutrient with enhanced bioactivities in our previous study. In this study, a hydrophobic nutrient, α-tocopherol (TOC), was successfully encapsulated into zein/CS complex. The fabrication parameters, including zein concentration, zein/CS weight ratio, and TOC loading percentage, were systematically investigated. The physicochemical and structural analysis showed that the electrostatic interactions and hydrogen bonds were major forces responsible for complex formation. The scanning electron microscopy study revealed the spherical nature with smooth surface of complex. TOC encapsulation was also evidenced by differential scanning calorimetry. The particle size and zeta potential of the complex varied from 200 to 800 nm and +22.8 to +40.9 mV, respectively. The kinetic release profile of the TOC showed burst effect followed by slow release. Compared with zein nanoparticles, zein/CS complex provided better protection of TOC release against gastrointestinal conditions, due to CS coatings. Zein/CS complex is believed to be a promising delivery system for supplementation or treatment of hydrophobic nutrients or drugs., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Physics and chemistry underpinned the remarkable advances in materials science that occurred during the 20th century, while biology is poised to provide the scientific underpinning for materials science advances of the 21st century. Biofabrication is the emerging approach to broadly apply biology's materials and mechanisms to create structure and function. Here, we describe one such biofabrication methodology, the use of tyrosinase to graft phenolics to the aminopolysaccharide chitosan. Phenolics are a broad class of abundant natural products and we provide results from a single phenolic reactant, caffeic acid, to illustrate the potential for enzymatically imparting functional properties to chitosan. We show that tyrosinase oxidation mediates the grafting of caffeic acid to chitosan and possibly even results in the covalent crosslinking of chitosan. When this enzymatic reaction is performed in a chitosan solution (pH<6), it is observed to induce a sol-gel transition. At higher pHs, chitosan forms an insoluble film and this enzymatic reaction can alter the film's mechanical properties. Importantly, caffeic acid grafting also confers redox-activity to the chitosan film, enabling the film to accept, store and donate electrons. The broader efforts to enlist tyrosinase to build macromolecular structures and impart functions are discussed. [ABSTRACT FROM AUTHOR]

Sensor-based chemical analyses commonly enlist either the molecular recognition capabilities of biology (e.g., enzyme biosensors) or advanced information processing algorithms (e.g., the electronic nose). Here, a hybrid approach is proposed in which an enzyme is used to 'filter' chemical information and write this information to a film which then serves as a permanent storage medium that can be 'read' repeatedly, interactively, and by multiple sensor modalities. This approach is demonstrated by analyzing common dietary phenols that are reported to offer health benefits. Specifically, the enzyme tyrosinase is used to convert these phenols into reactive quinones that graft (i.e., write) to a chitosan film. Grafting can be detected by optical, mechanical, and electrochemical sensors. Importantly, grafting confers redox activity to the films and this redox activity can be probed interactively by advanced electrochemical methods that allow the intrinsic redox reactivities to be compared, redox interactions to be identified, and biologically relevant redox activities to be examined. The transfer of chemical and biological information to a film is envisioned to provide broader access to the extensive capabilities offered by sensor technologies and signal processing methodologies. [ABSTRACT FROM AUTHOR]

Abstract: The selenite-loaded chitosan (CS) nanoparticles using tripolyphosphate (TPP) as a cross-linking agent with or without zein (a water insoluble corn protein) coating were prepared to obtain selenite supplement formulations with low toxicity and improved antioxidant property. Scanning electron microscopy observation showed selenite-loaded CS/TPP nanoparticles had a spherical shape with uniform diameter (100–300nm). The results demonstrated that particle size, surface charge, encapsulation efficiency, and release profile could be modulated by fabricating conditions. After coated with zein, the particle size maintained nanoscale (200–400nm) while encapsulation efficiency increased from 60% to 95%. The release profile was also prominently improved with zein coating, the released selenite reduced from 85% to 30% within 4h in PBS. In simulated gastrointestinal condition with enzymes, 93% of selenite released from non-coated CS/TPP nanoparticles into gastric fluid, however, the releasing rate decreased to 46% after coated with zein. Moreover, due to high antioxidant activity of CS, the in vitro antioxidant properties of selenite-loaded CS/TPP nanoparticles were significantly enhanced, compared with pure selenite. [ABSTRACT FROM AUTHOR]

A novel nanocomposite of silver/titanium dioxide/chitosan adipate (Ag/TiO 2 /CS) was developed through photochemical reduction using a chitosan adipate template. Chitosan served as a reducing agent anchoring the metal ions through Ag–N coordination bonds and electrostatic attractions, thus stabilizing the Ag/TiO 2 /CS product observed by Fourier transform infrared spectroscopy and X-ray diffraction patterns. Scanning electron microscopy observations revealed that the nanocomposite particles (50–100 nm) were deposited onto the chitosan adipate layer. The product exhibited high ζ-potentials from 30.1 mV to 33.0 mV during 60 days of storage. In addition, the nanocomposite demonstrated higher antimicrobial activity than AgNO 3 or nano-Ag particles at similar concentrations, as evidenced by the inhibition zone, minimum inhibitory concentrations (MIC), and growth curve. The nanocomposite reduced the Escherichia coli population by 6 logs after 24 h of incubation, and had an MIC value of 0.38 μg Ag/mL. These results suggest that Ag/TiO 2 /CS has the potential to be used as an antibacterial protective coating for fruit storage. [ABSTRACT FROM AUTHOR]